The past few years have witnessed a great popularity of digital and online videos and their applications. Streaming of video, both live video and recorded video, via, for example, internet, is getting more popular than traditional ways of viewing video such as television or rental of DVDs. A problem that may occur when streaming video is that the bandwidth of the internet connection over which the streaming is done is too low for the resolution (HD, 4K, 1080P, and the like) of the streamed video, or that the bandwidth of the internet connection is fluctuating. An insufficient bandwidth may cause the streaming video to stutter, which makes the video unwatchable due to lag. One way of preparing the video for being streamed on a limited bandwidth internet connection is rate control. Rate control plays an important role in video coding, where the rate control ensures the coded bit stream can be transmitted successfully and makes full use of the limited bandwidth. In other words, it is adjusting video output bits according to the fixed or variable bandwidth. Typically, rate control work with compression and frame rate, which often yields bad quality at low bitrates.
US 2004/120398 (Zhang et al.) disclose a method for adaptively encoding a video including a sequence of images, where each image is a picture of two fields. Each image of the video is encoded as a frame and rate-distortion characteristics are extracted from the encoded frames, while concurrently encoding each image of the video as two fields and rate-distortion characteristics are extracted from the fields. A parameter value λ of a cost function is determined according to the extracted rate-distortion characteristics, and a cost function is constructed from the extracted rate-distortion characteristics and the parameter λ. Then, either frame encoding or field encoding is selected for each image depending on a value of the constructed cost function for the image.
U.S. Pat. No. 6,226,3276 (Igarashi et al.) disclose an encoder that considers a frame representing a picture as comprised of areas. For each area, the encoder decides which of frame-based or field-based orthogonal transformation will be most efficient at reducing spatial redundancy in that area. For each area, the encoder decides which of frame-based or field-based predictive encoding will be most efficient at reducing temporal redundance in that area. The encoder encodes each area of the picture frame using the most efficient orthogonal transformation technique and using the most effective predictive encoding technique to produce an encoded signal. A decoder decodes the encoded signal. The encoded signal is recorded on a recording medium, transmitted over a transmission channel, or broad-cast.
“An adaptive divide-and-predict coding for intra-frame of H.264/AVC” (Piao et al.) disclose an intra-frame coding scheme proposed for progressive video sequences in H.264/AVC. In the proposed method, every other pixel is sampled either in a horizontal or vertical direction without any anti-aliasing filtering, and two sub-frames of the even-pixel and odd-pixel are then generated. The even-pixel and odd-pixel sub-frames are coded by the intra- and inter-frame coding methods, respectively. The proposed method can be expanded into a multi-level case in which the even-pixel sub-frame is again sub-divided into an even-pixel sub-frame and an odd-pixel subframe, and so on to further improve the coding efficiency.
There is thus a need for improvements within this context.